In the pharmaceutical industry, pharmaceutical compounds which are placed in vials must remain as pure as possible in order to ensure that the pharmaceutical compounds are effective when used. Vials and/or other small containers must be thoroughly cleaned and sterilized prior to being filled with pharmaceuticals to prevent contamination of the pharmaceuticals from residues, dust or other impurities on or in the vials.
One type of vial washer which is commonly used in the industry is an endless belt vial washer. Vials are inserted upside down into vial holder cups attached to the endless belt such that the open top of the vials face downward. The belt carries the vials through a series of cleaning stages where the vials are cleaned with steam or other cleaning fluids from above and below, and then blown dry. The cleaned vials are then unloaded from the holders and carried to a separate sterilization tunnel where the vials are sterilized.
In order to ensure that the vials are properly cleaned, the vials must be in an inverted position when they are inserted in the vial holder cups. If a vial is not inverted, it will hold cleaning fluid, and will potentially contaminate other vials if not immediately removed, and would clearly be unsatisfactory itself for further processing. The vial holder cups are provided with a tapered bottom portion, and, based on the reduced diameter of the open top of the vial in comparison to the closed bottom, if a vial is not properly inserted into a given vial holder cup, it will sit at a higher position in the vial holder cup than a properly inserted vial.
In order to detect when a vial has been improperly inserted into a holder cup, hold-down bars are pivotally mounted at a height of up to about 1/8 inch above bottoms of the inverted vials. A hold down bar is typically positioned above each row of vial holder cups, with the hold down bar being located in aligned slots in the row of cups. If a vial is improperly inserted into a vial holder cup, the improperly inserted vial contacts the hold-down bar, activating a sensor. The vial washer is then stopped until the vial is properly repositioned.
In the known vial washers, the position of the hold-down bars is sensed utilizing a photo-emitter and a photo-receiver positioned on opposite sides of the vial wash area. A beam of light is directed from the photo-emitter to the photo-receiver. If a hold-down bar becomes displaced due to an improperly positioned vial, the displaced hold-down bar interrupts the beam of light between the photo-emitter and the photo-receiver, signaling the vial washer to shut down until the vial is properly repositioned or removed.
Because the generally known vial washer assemblies have between 18 and 37 hold-down bars and, depending on the application, are 24-48 inches wide, the light beam must travel this distance unobstructed for the washer to operate automatically. However, during start-up, the vial washing area is more foggy than during normal washing operations due to steam and condensation being directed through the belt into the empty vial holders prior to vials being loaded. The excess steam and condensation can interrupt the beam from the photo-emitter to the photo receiver, resulting in a false signal indicating that a hold-down bar is out of place, when in fact the light beam between the photo-emitter and receiver has been interrupted by the steam or condensation inside the vial washer itself. The vial washer is then automatically shut down and the sensors must be overridden in order to successfully restart the cleaning operation.
The present invention is a result of observation of the problems with the prior art devices and efforts to solve them by providing a more reliable sensor assembly which detects when a vial is improperly inserted in a vial holder, but will not give a false signal due to visually obscuring environmental conditions such as steam and/or condensation.